1. Field of the Invention
The present invention relates to a process monitor for monitoring a semiconductor manufacturing process, such as a plasma process, and to a semiconductor manufacturing apparatus having a process monitor.
2. Prior Art
Conventionally, in a semiconductor manufacturing apparatus, a measurement of a plasma density or a temperature, etc., to optimally control a plasma process is carried out, for example, by inserting a plasma probe or a thermocouple into a plasma processing chamber at a time of development in a factory. However, as high-mix low-volume manufacture increases in LSI manufacturing, process conditions are made different and the plasma state must be measured each time the process changes. If, at each time, measuring by inserting a probe or the like is carried out, the measurement is very troublesome and a wiring, for measurement and control is necessary, which causes a disturbance in a measuring object. A simultaneous multipoint measurement is difficult and measurement at an area where the measurement is actually required is also difficult. Furthermore, a problem of contamination or a problem of decrease in operating rates, arises.
Recently, a sensor wafer, which is a sensor having no probe and can be carried in the same way as a normal silicon wafer, has been developed (see, for example, Yan Tran, Tim Yen and Bruce Bunn (UCLA) “Development of Lithium Batteries for Powering Sensor Arrays”, SFR Work shop, Nov. 14, 2001).
However, a battery, which is a power supply source for the wafer sensor, is deteriorated by repeated charging and discharging. A material of which the battery is made could contaminate a plasma processing chamber if the sensor wafer is broken by an unexpected accident or the like.